From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BCF1A34D3B3 for ; Mon, 10 Nov 2025 14:11:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762783907; cv=none; b=g6nt6OURLLHsVj7wsqQs5HJ67fftjjoGtPQLuACMz3fGqes6Qx/0ctXIZdttd1HUKetmTaw0qwS27BhM769ny9UiAV7xFcqNuUDMV9rgalYc6TZcMs2U80vsZIKtyIqxOZgBpCaee/zBdNkyK9wHFsnRqJ6tKU3fVqvNcu6cy8g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762783907; c=relaxed/simple; bh=Buq1MT0S7MubjcfDlzuiL8qsg8OhP5WDNgUJe5GnQE8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=eeDv08Wvf4mErUTsfuN4HUcyRWrvACuEBs3xRPLOGTVTKPnTg7gcLQsu190MGP4qUriQpiLjNLRe0B6U5f8LDJRfXVfC6yrPsj13Djr2ooN7n57SUhDauxG0JqbD7Py61lTSoH5JXnQRC+C6JieMb3ol79e3ztUKtLpgjBQsf2E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=WBUWdqii; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="WBUWdqii" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=GaeHzArTdI+oTKMXGP82IYfI26aTSt0HVq6Zx2NSCs4=; b=WBUWdqii/uf7SdtW/vcZd945LC ktYg/ZQWxo4gr3co3/3PCH5kIVTax039NCa6NXd+XOPVcNppZjDakXUGVIm63tScDkTUmFYuz0I0M oST0IozeUoFuroPoC17T44c5hcIp4+dTMg31+6mrNDdGTKFjY84ozHs8U17SNvmqm2qcLfQA8qexN 5g8kCH2eI18vUM08o6JL73Z8aQR6t2vc1ZkdBk4XEqoIHPyoG1zOq6ghDE2r4gUA51G6BMfEoenpM uy0BHO/LIIoaMLnjbulVHd5GRszC8dNp64FF5Taenuuo4e4M90VUsa3U+DE4xoaZENGnTB+JVjBPq qYgZiYsg==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vIRkk-0000000AqY7-0Ocu; Mon, 10 Nov 2025 13:16:14 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 6DE3D30029E; Mon, 10 Nov 2025 15:11:41 +0100 (CET) Date: Mon, 10 Nov 2025 15:11:41 +0100 From: Peter Zijlstra To: Shrikanth Hegde Cc: juri.lelli@redhat.com, mingo@redhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, dietmar.eggemann@arm.com, nico@fluxnic.net Subject: Re: [PATCH 2/2] sched/deadline: Use cpumask_weight_and in dl_bw_cpus Message-ID: <20251110141141.GZ3245006@noisy.programming.kicks-ass.net> References: <20251014100342.978936-1-sshegde@linux.ibm.com> <20251014100342.978936-3-sshegde@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251014100342.978936-3-sshegde@linux.ibm.com> On Tue, Oct 14, 2025 at 03:33:42PM +0530, Shrikanth Hegde wrote: > - cpumask_subset(a,b) -> cpumask_weight(a) should be same as > cpumask_weight_and(a,b) > > - for_each_cpu_and(a,b) to count cpus could be replaced by > cpumask_weight_and(a,b) > > No Functional Change. It could save a few cycles since cpumask_weight_and > would be more efficient. Plus one less stack variable. > > Signed-off-by: Shrikanth Hegde > --- > kernel/sched/deadline.c | 11 +---------- > 1 file changed, 1 insertion(+), 10 deletions(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 8b7c4ee41fd8..a18f64b2e47c 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -125,20 +125,11 @@ static inline struct dl_bw *dl_bw_of(int i) > static inline int dl_bw_cpus(int i) > { > struct root_domain *rd = cpu_rq(i)->rd; > - int cpus; > > RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), > "sched RCU must be held"); > > - if (cpumask_subset(rd->span, cpu_active_mask)) > - return cpumask_weight(rd->span); > - > - cpus = 0; > - > - for_each_cpu_and(i, rd->span, cpu_active_mask) > - cpus++; > - > - return cpus; > + return cpumask_weight_and(rd->span, cpu_active_mask); > } Right, let me stick that on top of the change I have in queue/sched/core